Bead curing finger mold

ABSTRACT

A tire bundle is molded in a mold cavity formed by closing a mold having upper and lower mold halves with intermeshing fingers ( 20, 24 ) for enclosing bead wires and providing a molded bead ring for placing in a bead apex mold.

TECHNICAL FIELD

This invention related to molding a tire bead and especially to curingthe rubber coating on the bead wires of a bead bundle which is held in apredetermined shape. The bead wires are held in place during thevulcanization so that when the bead ring is placed in a mold forinjection molding of an apex on the bead, the mold will not be damagedby out of place wires. The bead bundle is also cured in a circular shapeso that problems with pinching out of round beads are avoided during theclosing of the bead apex mold.

BACKGROUND ART

Heretofore as shown and described in U.S. Pat. No. 5,798,127, a beadbundle of rubber coated bead wires has been placed in an apex mold andheld in position by blades engaging the radially inner surface of thetire bead bundle. The apex-bead assembly is then formed by injection ofrubber into the apex mold cavity of the apex mold. If the bead wiresextend outwardly from the bead bundle, the mold may be damaged duringclosing causing shut down and costly repairs. With this method theunvulcanized bead bundle may be changed in shape by handling beforeplacing in the apex mold. Also the bead bundle may be distorted and comeapart during the injection process when rubber is being injected pastthe bead at high velocity and with great force.

Another object of the present invention is to provide a bead curingfinger mold further characterized by the upper fingers and the lowerfingers having sloped edges for guiding and compressing the bead bundlein a central position upon closing of the mold.

Another object of the present invention is to provide a bead curingfinger mold further characterized by the upper fingers and the lowerfingers having molding surfaces providing a circular molding membersurface of the mold with a precise predetermined diameter of the beadbundle upon closing of the mold.

Another object of the present invention is to provide a bead curingfinger mold wherein the bead bundle is a tire bead having a plurality ofwires wrapped in a the bead bundle and coated with an elastomericmaterial further characterized by means for heating the mold forvulcanizing the elastomeric material.

Another object of the present invention is to provide a bead curingfinger mold further characterized by the upper fingers and the lowerfingers having extensions extending beyond the molding surfaces forguiding the bead bundle and providing recesses for receiving theextensions in the closed condition of the mold.

Another object of the present invention is to provide a bead curingfinger mold further characterized by the lower finger mold half beingraised to close the mold and the upper finger mold half has spaced apartspring loaded ejector fingers for retracting upon closing of the moldand for extension upon opening of the mold to transfer the bead bundleto the lower finger mold half.

Another object of the present invention is to provide a bead curingfinger mold further characterized by the lower mold half havingcircumferentially spaced apart ejectors and bead holders extendingupwardly through the lower finger mold half for holding the bead bundlein the lower position of the lower finger mold half prior to closing ofthe mold and ejecting the bead bundle upon lowering of the upper moldhalf after vulcanization of the bead bundle.

In U.S. Pat. No. 5,262,115, an apex bead assembly mold for injectionmolding the apex assembly is shown where the rubber coated bead bundlesare held in place on a cylindrical core by spaced-apart coaxial roundrings arranged in side by side relation and engaging the axiallyextending inner surfaces and the radially extending inner surfaces ofthe beads so that when half molds are mounted around the core with thebeads held in place, apex portions may be injection molded. Thereafter,the mold halves are removed and the bead apex assemblies pulled off therings. During the injection process the unprotected bead bundle ofunvulcanized rubber may be distorted or come apart due to high velocitymovement of the rubber past of the bead.

DISCLOSURE OF THE INVENTION

This invention relates to a mold for heating and enclosing a circularmember comprising a first mold member, a second mold member movable intoengagement with the first mold member to provide a mold cavitycharacterized by the first mold member having a pluralitycircumferentially spaced first fingers, the second mold member having aplurality of circumferentially spaced second fingers movable intomeshing engagement with the first fingers upon closing of the mold bymovement of the first mold member towards the second mold memberproviding a circular mold cavity for the circular member.

This invention further relates to a bead curing finger moldcharacterized by a plurality of circumferentially spaced lower fingersdisposed in a lower ring, a plurality of circumferentially spaced upperfingers disposed in an upper ring, the lower ring being positioned in agenerally horizontal position for supporting a bead bundle, and theupper ring being positioned over the lower ring with the lower fingersinterposed between the upper fingers in a closed position of the moldfor containing and guiding the bead bundle and providing spaces alongthe lower fingers and the upper fingers to accommodate variations insize of the bead bundle.

This invention is also directed to the construction of a tire beadcomprising multiple revolutions of metal wires coated with rubber andwound in a circular configuration to form a bead bundle characterized bythe bead bundle being cured in a bead curing finger mold having aplurality of circumferentially spaced lower fingers disposed in a lowerring in a generally horizontal lower position for supporting the beadbundle, a plurality of circumferentially spaced upper fingers disposedin a generally horizontal upper ring positioned over the lower ring withthe lower fingers interposed between the upper fingers in the closedposition of the mold for containing and guiding the wires of the beadbundle and providing spaces along the lower fingers and the upperfingers to accommodate variations in size of the bead bundle duringvulcanization of the bead upon application of heat to bead curing fingermold.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a front view in perspective of a finger mold embodying theinvention shown mounted in a press.

FIG. 2 is an elevation with parts broken away of the upper and lowermold halves shown in FIG. 1 removed from the press with the bead ringshown lifted from the lower mold.

FIG. 3 is a cross sectional view of the molds taken along the plane ofline 3—3 in FIG. 2.

FIG. 4 is a plan view of the lower mold half taken along the plane ofline 4—4 in FIG. 2.

FIG. 5 is an enlarged fragmentary sectional view of the spring forremoving the bead from the upper mold half.

FIG. 6 is an enlarged fragmentary schematic sectional view of the upperand lower finger mold halves shown in FIG. 2 with the bead bundle heldby the fingers without bottoming of the finger mold halves.

FIG. 7 is a view like FIG. 6 showing the bead ring after molding andbefore removal from the lower finger mold half.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, a bead curing finger mold 10 embodying theinvention is mounted in a hydraulic press 12 and has an upper fingermold half 14 and a lower finger mold half 16 movable together and apartupon opening and closing of the press. In the embodiment shown, thepress 12 provides a pressure of 7 tons (7.11 metric tons) plus or minus5 tons (5.08 metric tons) and the diameter of the bead is 22.50 inches(57.15 cm), however, with this press, medium radial truck tire beads ofdiameters having a range of 17.50 inches (44.45 cm) to 24.5 inches(62.23 cm) may be molded with finger molds of this type.

Referring to FIGS. 1-4, the lower finger mold half 16 is mounted on abottom press plate 18 and includes a plurality of circumferentiallyspaced apart lower fingers 20. Vertically movable ejector and beadholders 22 are mounted in the bottom press plate 18 at circumferentiallyspaced positions around the lower finger mold half 16 for holding a beadbundle 23 prior to closing the press 12 and ejecting the vulcanized beadafter the curing cycle.

Referring to FIGS. 2, 3 and 5, the upper finger mold half 14 has aplurality of circumferentially spaced upper fingers 24 mounted on a toppress plate 26 of the press 12. Four spaced apart upper ejector fingers27 are individually slidably supported and are spring loaded on theupper finger mold half 14 and have four posts 28 slidably mounted incollars 30, fastened to the upper finger mold half 14. Coil springs 32are disposed between the collars 30 and the upper ejector fingers 27 tourge the ejector fingers downward into engagement with the bead bundle23 to eject the bead bundle and separate the bead bundle from the uppermold half 14 as the mold 10 opens. In operation, the press 12 is openedto the position shown in FIG. 1 with the ejector and bead holders 22 ina position above the lower finger mold half 16. The bead bundle 23 isthen placed over the lower fingers 20 on the bead holders 22. The beadbundle 23 comprises a ring of bead wires wound and coated with rubber ina bead ring in a manner well-known in the art. The bottom press plate 18is then raised vertically lifting the bead bundle 23 off the ejector andbead holders 22. As shown in FIG. 7, tapered side surfaces 38 of thelower fingers 20 preferably have the same slope as a bead surface 40relative to the axial direction A—A, which in this embodiment is anangle X of 15 degrees. However, in other embodiments, this angle mayrange from 0 to 45 degrees. The angle X is normally the same angle asthe angle of the surface of the rim of the wheel on which the tirehaving this bead bundle 23 is mounted.

The press 12 is closed with the bottom mold plate 18 raised into aseating position with the top press plate 26. The lower finger mold half16 is raised into position so that the lower fingers 20 are in meshingengagement with the upper fingers 24 as shown in FIG. 6. Steam or otherheat transmitting material may then be provided in the press forvulcanizing the bead bundle 23 into a compact bead.

As shown in FIGS. 6 and 7, during the closing operation the movement ofthe lower finger mold half 14 upward towards the upper finger mold half14 is stopped by the compression of the bead bundle 23. There is nobottoming out of the upper finger mold half 14 against the lower fingermold half 16. This is advantageous because it provides a compact beadring even though there may be variations in the size of the bead bundle23. Variations may be accommodated in spaces 40 at the edges of theupper fingers 24 and lower fingers 20.

After vulcanization, the press 12 is opened and the springs 32 urge theejector fingers 27 downward ejecting the bead bundle 23 as the press 12opens. The ejector and bead holders 22 protrude through the lower fingermold half 16 and lift the vulcanized bead bundle 23 to the positionshown in FIGS. 2 and 3 as the bottom mold plate 18 is lowered.

While a certain representative embodiment and details have been shownfor the purpose of illustrating the invention, it will be apparent tothose skilled in the art that various changes and modifications may bemade therein without departing from the spirit or scope of theinvention.

Having thus described the invention it is now claimed:

What is claimed is:
 1. A bead curing finger mold comprising a pluralityof circumferentially spaced lower fingers disposed in a lower fingermold half, a plurality of circumferentially spaced upper fingersdisposed in an upper finger mold half, said lower finger mold half beingpositioned in a generally horizontal position for supporting a beadbundle, and said upper finger mold half being positioned over said lowerfinger mold half with said lower fingers being interposed between saidupper fingers in a closed position of said mold for containing andguiding said bead bundle and providing spaces along said lower fingersand said upper fingers to accommodate variations in size of said beadbundle.
 2. A bead curing finger mold according to claim 1 furthercharacterized by said lower finger mold half being raised to close saidmold and said upper finger mold half has spaced apart spring loadedejector fingers for retracting upon closing of said mold and forextension upon opening of said mold to transfer said bead bundle to saidlower finger mold half.
 3. A bead curing finger mold according to claim1 further characterized by said lower finger mold half havingcircumferentially spaced apart ejectors and bead holders extendingupwardly through said lower finger mold half for holding said beadbundle in the lower position of said lower finger mold half prior toclosing of said mold and ejecting said bead bundle upon lowering of saidupper mold half after vulcanization of said bead bundle.
 4. A beadcuring finger mold according to claim 1 further characterized by saidupper fingers and said lower fingers having sloped edges for guiding andcompressing said bead bundle in a central position upon closing of saidmold.
 5. A bead curing finger mold according to claim 4 furthercharacterized by said upper fingers and said lower fingers havingmolding surfaces providing a circular molding member surface of saidmold with a precise predetermined diameter of said bead bundle uponclosing of said mold.
 6. A bead curing finger mold according to claim 5wherein said bead bundle is a tire bead having a plurality of wireswrapped in said bead bundle and coated with an elastomeric materialfurther characterized by means for heating said mold for vulcanizingsaid elastomeric material.
 7. A bead curing finger mold according toclaim 5 further characterized by said upper fingers and said lowerfingers having extensions extending beyond said molding surfaces forguiding said bead bundle and providing recesses for receiving saidextensions in the closed condition of said mold.